Sorry, you got me thinking, so I tested using Outlook 2007 imap, which does fail on TLS 143/993, but works as expected using SSL
I know certainly on our servers, SSL is disabled, and therefore only TLS could work, and also my Iphone5 is set to TLS, which also works lovely, but the question is, is setting SSL in outlook, using TLS, so I tested it (see below - certain details changed), which shows TLS in use.
I am not sure though if this is just a microsoft issue, as my iphone does connect using TLS, and in daily use.
I hope that helps a little
1134.**Finished negotiating SSL - algorithm is TLS_RSA_WITH_AES_256_CBC_SHA
1135.<~~ OK [CAPABILITY IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA IDLE] Courier-IMAP ready. Copyright 1998-2003 Double Precision, Inc. See COPYING for distribution information.
1288.~~>A LOGIN [email protected] password
1290.<~~A OK LOGIN Ok.
1427.~~>B LIST “” *
1429.<~~* LIST (\HasNoChildren) “.” “INBOX.Learn Spam”
B OK LIST completed.
11547.~~>C SELECT INBOX
11548.<~~* FLAGS (\Draft \Answered \Flagged \Deleted \Seen \Recent)
C OK [READ-WRITE] Ok
21669.<~~* BYE Courier-IMAP server shutting down
D OK LOGOUT completed
2017-01-10 09:51:12.064655500 tcpserver: end 24809 status 0
2017-01-10 09:51:12.063808500 INFO: LOGOUT, [email protected], ip=[216.68.n.n], headers=0, body=0
2017-01-10 09:50:51.716343500 INFO: LOGIN, [email protected], ip=[216.68.n.n], protocol=IMAP
2017-01-10 09:50:51.420211500 INFO: Connection, ip=[18.104.22.168]
2017-01-10 09:50:50.693890500 tcpserver: ok 24809 mydomain.url:::ffff:5.n.n.n:993 :::ffff:216.68.n.n::52868
2017-01-10 09:50:50.693889500 tcpserver: pid 24809 from 216.68.n.n